Material possibly mined (5)
I believe the answer is:
denim
'material' is the definition.
(type of fabric)
'possibly mined' is the wordplay.
'possibly' indicates anagramming the letters.
'mined' anagrammed gives 'DENIM'.
(Other definitions for denim that I've seen before include "Fabric used for jeans" , "Hard-wearing material seen in jeans" , "Tough cotton fabric" , "Thick cotton cloth" , "Durable material" .)